The curtain call mentioned is, of course, the after-credits scene. In order to reach this point, you can't interrupt the ending by skipping. I do not know if you can press anything at all, but it was suggested to just lay the controller down and let the credits roll about normally.
*This scene will only play if the Normal or True ending has been achieved.
Once that has finished, you should receive a cutscene where a merchant is talking to you (the author of the books) and describes how Erion is recovering from the tragedy. He will offer you a Valentine coin for your troubles and this is the coin mentioned. It will also unlock the trophy as soon as it disappears from his inventory (and into your pseudo-inventory).